Electric incandescent igniter



Nov. 19, 1929. K. scHAFx-'LER REKTE GLssL ELECTRIC INCANDESCENT lGNITER Filed July 24, 1928 Patented Nov. 19, 1929 rica ELECTRIC INCANDESCENT IGNITER Application led July 24, 1928, Serial N The invention relates to electric low tension or incandescent igniters and has for its object to provide for enabling the incandescent wire of such igniters to be arranged in the required length on the electrodes in such mannerthat the ignition by any stray currents is prevented. For such purpose a high ohmic wire having a diameter of about 0.03- 0.05 m/m and a minimum length equal to 30 m/m is wound on the electrode carrier so as to be insulated, the ends of such wire being connected to the corresponding electrodes and the windings being spaced apart by a distance which prevents the windings from heating substantially each other.

A portion of the wound wire, by preference a minor portion thereof may be surrounded by the igniting mass, whereas the remaining or major portion is left free or embedded in a refractory mass.

In the drawings:

Fig. 1 shows the heating or incandescent element of the igniter having an insulated filament wound thereon, in front view. Fig. 2 is a vertical section through the igniter. Fig. 3 is a cross section through the same. Figs. 4 and 5 show the incandescent element of a pill igniter, the filament of which is surrounded by insulating material. Fig. 6 shows the same pill igniter but having a bare wire or filament. Fig. 7 shows a high ormic low tension igniter with solid head and Fig. 8 a high ohmic low tension igniter with loose igniting material.

In the arrangement according to Figs. 1-3 the two electrodes l and 2 are separated by hard paper 3 or any other insulating layer. Round the center portion of the insulating layer 3 and round the electrodes 1. 2 the filament or wire 4 is transversally wound 1n required length. It has been found that a wire having a thickness equal to 0.03-0-05 m/m and a minimum length equal to 30 m/m entirely excludes the ignition by .any stray currents. Such wire is coated with an in* 295,061, and in Austria December 1, 1927.

sulating covering for example it is enamelled, and the ends of the wire are connected say by soldering to the electrodes cemented to the hard paper layer 3. The heating element thus built up is inserted ina brass shell 5, whereupon `the explosive or igniting material 6 is filled in and the shell closed.

. After the filament 4 being coated with an insulating covering has been wound round the two insulated electrodes l, 2 and connected conductively to the two insulated electrodes 1, 2, the latter may be dipped in an igniting mass 6, whereby the head of a pill igniter is produced, as shown in Figs. 4 and 5. The said igniter head is cast in brass or paper shells.

The pill igniter may also be provided as shown in Fig. 6 with a hare incandescent wire 4, but the windings must be arranged in such manner that they cannot Contact each other, and then the two electrodes are provided with an insulating covering of paper or the like, i. e. between the wire 4 and the electrodes 1, 2 an insulating layer must be provided. In both cases, of course the igniting material is ignited by correspondingly heating the filament. In such manner electric low tension or incandescent igniters may be manufactured, with which the minimal intensity of the igniting current may be adjusted at will by the cross section of the wire and the `required minimal voltage by the length of said wire. Therefore it is possible to manufacture for example low tension igniters the minimum current intensity of which is 0.5 amp. and the minimum voltage 2O volt or more, i. e. igniters, which are not ignited by a lower current intensity and voltage, so that the undesired effect of the stray currents is excluded.

The filament may also be arranged in such manner that only a corresponding small portion of the entire filament is surrounded by the explosion or igniting material 6 (Figs. 7, 8) whereas, the remainder portion of the rial, Fig. 7, the shell 9 may be left open at 12, whereas in igniters with loose igniting matef rial a closure 13 is provided. In .the latter case the igniting material V6 is separated from the refractory mass by a disklll.

The arrangement (Figs. 7 and 8) has the advantage, that in such high ohmic low ten'- sion igniters a much lessheat accumulation takes place, so that they are much more resistive to stray currents than the igniters shown in Figs. 1-6. The largest portion of the heat caused by the current Yilowing through the filament has therefore no effect on the igniting material.v YThe ,stray ,current iiows continuously ork constantly through'the low tension igniter and heats its windings,

whichagain iniiuence eachother' by'heat radiation. Now, ifgall windings are `embedded in the igniting material, as is Vthe case with the igniters shown in Figs.`1-6, already a current intensity of say 10()` milliamperes is sufcient to heat the'y igniter-,by the current continuously passing therethrough in such manner, that the same isignited. With the use of the same filament having the same diameter the arrangement according to Figs. 7 and 8 requires more than 200 milliamperes for igniting the low tension igniter, if a cur rent passes continuously through it.` Now if an igniter according to Figs. 1;-6 has a resistance equal to 100 ohms, the limit, at which no igniter of the group can be ignited by the permanent or constant current amounts to 10' volts and 1 milliampere, whereas in the igniters shown in Figs. 7 and 8 vwith a resistance equal to 50 ohms already at a current voltage equal to 10 voltsy and a current intensity equal to 0.2 milliampere the low tension igniter is no more ignited.

The low tension igniter shown inFigs. 7 ,.8 has therefore the-advantage, that with the half of resistance of the filament or'with less expenditure (length) of the latter theI equal degree of safety against stray currents is obtained, and assuming that the resistance of the devices shown in Figs. 7 and 8 is equal to that of the devices shown' in Figs.11-6., say

at 100VV ohms,A stray currents up to 2O vol-ts cannot effect Vthe ignition'. Since vthe Vheat Vbeing produced by the current is lost and-.at the other hand the resistance isV increasediby heating, by the devices shownV inrFigs. 7 and 8 a higher Ysafety against stray currents will be obtained by heating the filament, Whereas in the devices shown in; Figs; 1 6Y the heating caused 'by strayl 'currents promotes the ignition, sincef'theentire filament is'surro-unded by the igniting material. The first named arrangement has the advantage thatthe very igniting current with equal safety against stray currents may have only half of the voltage and intensity, therefore theJ igniting machines have less Weight and cause lower prime costs. At the other hand it is also possible to ignite relatively larger series of the high ohmic low tension igniters (Figs. 7, 8) with the voltages of heavy current allowed in coal mines. 'Y

VIn all cases the windings of the wire are Vwidely spaced apart for' preventing the windings from heating substantially each other.

'As already mentioned the limit of resistance of ohms is materially reduced'by the igniters shown in Figs. 7 and S, since by such high ohmic incandescent igniters the equal safety against stray rcurrents is already obtained at 50 ohms as by the igniters shown in Figs. 1-6,a t a resistance equal to 100 ohms.

What I claim vis f i 1. In an incandescent igniter electrodes an electrode carrier, an incandescent wire wound Aon the electrode carrier andV roundthe-electrodesftransversally in respect to the longitudinal directionof the electrodes and being insulated therefrom, the wire'living a diameterV equal .to 0`.03-0.05.m/m and a vminimum length equal to 30 11i/ni, the. ends of said wire being conductively connected tothe electrodes and the windingsof the wire being .widelyV spaced apart for preventing them from substantially heat-ing each other. Y

Y 2. In an incandescent igniter electrodes an electrode carrier, a sheetofinsulating material cemented to the outer surface of the elec` trodes, a bare incandescent wire woundon the electrode carrier and. round lthe electrodes transversally in respect tothe longitudinal direction of the electrodesthe wire having a diameter equal to 0.03-0-O5 ni/m and a minimum length equal tov 30 m/m, the ends of said wire being conductively connected to the electrodes and the windings ofthe wire being widely spacedv apart for Vpreventing them from substantially heating each other.

3. In an Vincandescent igniter; electrodes,

an electrode carrier, anincandescent wire IOO coveredby insulating ma-terialv and vwound Aon the electrode carrierrand round the elec'- trodes transversally in respect to the longitudinal directionl of the electrodes,vthe wire having a diameter equal to` 0.030.05m/m and a minimumy length equal to 30m/m, the ends ofA saidv wire being conductifvely con- Vnectedto'the electrodes and the windings of Vit() the wire being widelyspacedapart for preventing them from substantially heatingeacl'i other. u Y

4. Inv an incandescent igniter electrodes, an electrode carrier, an incandescent wire wound ontheelectrode carrier and round the elec'.- Y trodes and beingl insulated therefrom, the

ends of said wire being connected to'said elecv trodes, an igniting mass, in which a portion 

